Light Is a form of energy. Light is needed to see things around us. We are to able see the beautiful world around us because of light. We can read a book, see pictures in a marazine, and watch television and movies due to the existence of light. And it is light which makes us see our image in a looking mirror. We detect light with our eyes 👀. Through we see the various objects (or things) around us with our eyes but eyes alone cannot see any object.
We also need a source of light to make objects visible. For example, we cannot see any object in a dark room or in the darkness of night because there is no light in a dark room or in the night to make objects visible.
But as soon as an electric bulb 💡 (a tube- light or a torch, etc.) is switched on and light falls on the objects to see that object. This light may have been emitted by the object itself or it may have been reflected by the object.
Light enable us to see objects from which it comes or from which it is reflected. For example, the sun gives out light. We can see the sun because the light coming from the sun enters our eyes. The objects like the sun, other starts, electric bulb, tube- light, torch, candle and fire etc., which emit their own light are called luminous objects. We can see the sun luminous objects due to the light emitted by them.
Through luminous objects are very small in number but they help us to see a large variety of non- luminous objects around us. The objects like flowers, a chair or a table do not have light of their own but even then we are able to see them.
This can be explained as follows: Through the objects like a flower, a chair or a table, etc., do not emit light themselves, we can see them by the light which they reflect (or scatter) by taking it from a luminous object like the sun or bulb light falls on a flower or chair (or any the sunlight or bulb light falls on a flower or chair (or any other object), some light is reflected towards us. And when this reflected light enters our eyes, then we are able to see the flower or chair (because to our eyes, this light appears to be coming from the flowers or chair).
Those objects which do not emit light themselves but only reflect (or scatter) the light which falls on them, are called cnin- luminous objects. A flower, chair, table, book, trees, other planets, human being, fan bed, mirror, diamond, walls, floor, and road etc are all non- luminous objects. In fact, most of the objects around us are non- luminous objects. We can see the non- luminous objects because they reflect light (received from a luminous object) into our eyes.
Even the moon is a non- luminous object (because it does not have its own light). We can see the moon because it reflects the sunlight falling on its surface towards us (on the earth). From the above discussion we conclude that light is a from of energy which causes in us the sensation of sight. Light travels in straight lines. The fact that va small source of light casts a sharp shadow bend easily and go behind the opaque object, then no shadow could be formed. We will now discuss the nature of light.
